Research by Brenda Tubana, PhD, Louisiana State University

The objective of this study was to compare, for use in Louisiana wheat production, the efficacy of a liquid silicon (Si) fertilizer (Huma Gro® Sili-Max®) with a commonly used dry Si source (steel slag) and another Si source (wollastonite) often used in research as a suspension. Silica deposition is an important barrier for foliar fungal diseases.

The wheat field study was conducted at Louisiana Ag-Center Research Stations. Silicon (Si) treatments were replicated four times and arranged in a randomized block design. There were 2 Huma Gro® Sili-Max® (10% Si) treatments (as a foliar band, and as foliar broadcast sprayed evenly over the entire plot). Each treatment was applied twice within 2 weeks at the onset of internode elongation (Feekes growth stage 5). The dry silicon sources (wollastonite [23% Si] and steel slag [11% Si]) were applied and incorporated into the soil prior to planting. Wheat leaf samples were collected one week after the application of silicon solution sources and evaluated for silica bodies (phytolith) deposition and percentage using scanning electron microscopy and energy dispersive x-ray analysis.

Sili-Max® foliar band and Sili-Max® foliar broadcast increased grain yield by 10 and 7 bu/ac, respectively, in reference to the control plot (Fig. 1). It is important to note that the total silicon applied using Sili-Max® solution was substantially lower (0.064 to 0.128 lb Si/ac) than the dry wollastonite and steel slag silicon sources (250 lb Si/ac). The state average wheat yield was low that year due to a mild winter that affected the wheat vernalization. Sili-Max® foliar band had the numerically highest straw yield at 7,941 lb/ac.

The accumulated silica bodies (phytolith) were 0.69% and 0.60% with Sili-Max® foliar broadcast and Sili-Max® foliar band treatments, respectively while the control had 0.53%.

Conclusions
Huma Gro® Sili-Max® applied as foliar band at a rate 3,900 times less than the dry silicon sources contributed to higher grain yield and straw yield, while the application of Sili-Max® as a foliar broadcast at a rate 1,900 times less than the dry silicon sources led to high Si deposition in wheat leaves.